把 Android Studio 升级版本后，运行 Flutter 项目报错如下

../../../Applications/flutter/packages/flutter/lib/src/material/animated_icons.dart:9:8: Error: Not found: 'dart:ui'
import 'dart:ui' as ui show Paint, Path, Canvas;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/animated_icons.dart:10:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/app.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' as ui;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/app_bar_theme.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/arc.dart:6:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/banner_theme.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/bottom_app_bar_theme.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/bottom_navigation_bar_theme.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/bottom_sheet.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;
       ^
../../../Applications/flutter/packages/flutter/lib/src/material/bottom_sheet_theme.dart:5:8: Error: Not found: 'dart:ui'
import 'dart:ui' show lerpDouble;

查询后才发现，之前安装的 Flutter 插件升级后不见了，Dart 插件还在，这可真是莫名其妙。看下一下你的 IDE 运行图标这是不是没有 Flutter 。如果是的话，肯定也是这原因。

但重新安装插件重启后，运行项目没问题，但运行单元测试还是报上面的错。这是因为 a.dart并不是 Flutter Tester 的单元测试。

将你的文件选择添加。

再运行就行了，记得给单元测试添加依赖，希望以上帮到了你。

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